The present invention relates to a movement control device for controlling a movement of a movable member, more particularly, it relates to a movement control device which controls a movement of a movable member such as movable sorting trays, onto which sheets transferred from a sheet processor are received, in a sorter, as a movable distribution unit for distributing sheets to stationary sorting trays in a sorter, as a movable sheet rest, on which a large number of sheets are stacked, in a feeder for feeding the sheets one by one to a sheet processor, and so on.
As a conventional apparatus which includes a movable member and a movement control device for controlling the movement of the movable member, a sorter is well-known in which a plurality of movable sorting trays as the movable member are collectively moved up or down so that one of the sorting trays is successively moved to a predetermined sheet receiving position in a sheet receiving operation or to a predetermined sheet take-out position in a sheet take-out operation under the control of the movement control device, or a sheet feeder is also well-known in which a sheet rest as a movable member is provided for receiving a large number of sheets thereon, and the sheet rest is moved up in accordance with a feed of the sheets, under the control of the movement control device.
As being apparent to the description above, it is necessary to stop the movable member in a predetermined position precisely. However, the movable sorting trays or the movable distributing unit in the sorter and the sheet rest in the sheet feeder are stopped and moved frequently and repeatedly. Accordingly, even though an error in the stop position is set to be small, the errors will be superposed with every stop operations and therefore the amount of the total errors in the stop position will increase considerably. As a result, the amount of each error must be considerably small in the conventional sorter or feeder.
Further in stop control operation of the conventional sorter or feeder, the initial timing of the stop operation of the drive motor is set to be constant nevertheless the moving speed is high or low; the moving direction is up or down; and the stacking load such as a stacking sheets number is large or small. Accordingly, even though the amount of each error can be set to be considerably small, it is difficult to stop the movable member in a predetermined position precisely.